Buzhov Borian T, Lemmers Richard J L F, Tournev Ivailo, Dikova Chayka, Kremensky Ivo, Petrova Julia, Frants Rune R, van der Maarel Silvère M
Department of Neurology, Sofia Medical University, Sofia, Bulgaria.
Hum Genet. 2005 Mar;116(4):262-6. doi: 10.1007/s00439-004-1237-0. Epub 2005 Jan 12.
Facioscapulohumeral muscular dystrophy (FSHD) is caused by contraction of the D4Z4 repeat on chromosome 4q. Genetic confirmation of the clinical diagnosis of FSHD is complicated by the presence of a homologous repeat on chromosome 10q and the frequent repeat exchanges between both chromosomes. Here, we describe the genetic evaluation of an FSHD patient with a complex D4Z4 allele constitution in which the potentially pathogenic allele seemingly resides on chromosome 10, despite FSHD being exclusively linked to chromosome 4. Complementary allele typing and segregation analysis confirmed the clinical diagnosis of FSHD by revealing the chromosome 4 origin of the pathogenic allele in the presence of two exchanged repeat arrays, one on chromosome 4 and one on chromosome 10, an allele constitution that cannot be identified by conventional DNA diagnosis.
